Question

Which one of the following is not a vestigial structural in Homo sapiens?

• A. Third molar
• B. Epiglottis
• C. Plica semilunaris
• D. Pyramidalis muscle

Answer 1

Answer: (B)

Epiglottis

Plica semilunaris is a vestige of the third eyelid and represents a fold in the conjunctiva of the human eye. Birds and reptiles have well developed the third eyelid.

Pyramidalis muscles are small, insignificant muscles of triangular shape that inferiorly arise from pubis and medially inserts into linea alba. Its absence does not affect human physiology as it is not found in 20% people.

Third molar, the wisdom teeth, is also non-functional structure as a reduction of jaw size during evolution made it unfit for the smaller jaw of human as compared to those of human ancestors.

Epiglottis is a cartilaginous structure that covers the glottis during the process of swallowing to prevent the entry of food into the trachea. The poorly developed/non-functional organs of recent forms of organisms which were fully developed and functional in related ancestral forms are referred to as vestigial organs.

So, the correct answer is option B.